Hopefully the list is long.
Jim as an early supporter and promoter in the high-fidelity world, may i offer a suggestion you may have already done something about, (bear in mind my suggestion a decade ago regarding perusing the high-fidelity world did come true)....
I would marshal my efforts and resources on Youtube, Netflix, Hulu and other web-based media- people are cutting the cord, moreover, those who have JRiver are primarily tech savvy folks. I mention due to an alarming fact, it is easier to access web media through cheap dvd players/ roku, built-in apps in TV's than MC18. It should absolutely be the other way around. I have seen your previous response that MC18 was superseded, and updates are nearly free, fine- this is the time to prove that point with MC20.
BTW, at audio shows I have been promoting the fact that the largest free audio library is now on YouTube, some will soon be in 4K and High Rez.
Your foot soldier